Download The value of Surtsey for ecological research

The value of Surtsey for ecological research
KRISTÍN SVAVARSDÓTTIR1 & LAWRENCE R. WALKER2
Soil Conservation Service, Keldnaholt,112 Reykjavík, Iceland
2
School of Life Sciences, University of Nevada Las Vegas,
4505 Maryland Parkway, Las Vegas, Nevada 89154-4004 USA
E-mail: [email protected]
1
ABSTRACT
Ecological research on Surtsey spans over 40 years of measurements, including monitoring of individual
plants early on and later establishment of permanent plots with estimates of vegetation cover. In this paper
we discuss the value of these studies for primary succession and the importance of strict control of access
to the island. The long-term data set from Surtsey contains detailed demographic data, and they provide
the opportunity to address aspects of species interactions, island biogeography, and nutrient dynamics. We
conclude that Surtsey is unique for primary succession because the study provides a thorough census of
an entire island since it was created, combined with minimal human influence because of the restricted
access to the island.
INTRODUCTION
Ecological research on Surtsey has provided
an unusual record of plant and animal colonization. Vascular plants, bryophytes, lichens, fungi,
birds and invertebrates have been monitored on
the island (Baldursson & Ingadóttir 2006). These
data are unusual because they span over 40 years
of measurements, they include several decades of
monitoring individual plants, they allow one to
distinguish between arrival and establishment of
a species, they highlight how the interactions of
birds, nutrients and plants impact primary succession and they provide a thorough census of an
entire island. These are all very important aspects
of this data set. However, what truly makes Surtsey
unique is the minimal human influence. Set aside
as a Nature Reserve in 1965 (category Ia according
to the IUCN classification), Surtsey is accessible
only by a limited number of people, mostly biologists and geologists and a crew that maintains the
hut. Each of these teams limits its stay so people
are on the island less than two weeks each year.
Surtsey Research (2009) 12: 149–151 www.surtsey.is
The Surtsey Research Society manages the island
on behalf of the Environment Agency of Iceland.
Surtsey was added to the World Heritage List of
UNESCO in July 2008. Natural remoteness of some
studies of succession make human visits to study
areas unlikely (e.g., landslides in the mountains of
western New Zealand, glacial moraines in Alaska
and Canada, uninhabitable volcanic islands in the
Pacific) but we know of no other study of primary
succession in the world where human visitation is
so restricted. Such restricted access is extremely
valuable to the study of primary succession.
We were both privileged to be guests of the biological research team that visited Surtsey for five
days in July 2003. Our comments that follow come
from our impression during that visit and lifelong
interests in primary succession in general, research
on Surtsey in particular and the interactions of science and society. The aim of this paper is to address the value of on-going research on primary
succession in Surtsey.
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RESEARCH VALUE
Long-term data
Primary succession involves the development of
plant and animal communities and soil formation
following such severe disturbance that little or no
biological legacy remains. Typically this process
takes decades or centuries before well-developed
soils appear, so long-term studies are essential.
Surtsey is one of only several studies of primary succession with such long-term data. Others include
volcanic surfaces on Krakatau, Indonesia (since
1908), glacial moraines at Glacier Bay, Alaska, USA
(since 1923) and dunes in Cooloola, Australia
(since 1962). See Walker and del Moral (2003) for
details. On Surtsey, we expect stable communities
to take several hundred to several thousand years
to develop, based on similar histories on the nearby Westman Islands. Minimal human interference
allows us to examine this process of succession in
its natural state.
Detailed demographic data
Marking individual plants as they colonize Surtsey has provided a remarkable record of natural
invasion processes and species dynamics (Fridriksson 1978, 1982, 1992). Although data collection
has now logically gone to plot-based sampling as
the number of individuals has grown, such demographic data could be explored further. A potential
use of the mapped plants around the entire island
is to explore secondary dispersal from species already on the island. How individual species impact
primary succession is best examined in such a field
laboratory where details exist on the populations
of individuals and individual species.
Species interactions
Surtsey is also an excellent setting in which to
explore how species interact. One of the most important lessons from Surtsey is that gull colonies
introduce nutrients and plants, and locally change
successional change in dramatic ways (Magnússon
& Magnússon 2000). This study has highlighted
the importance of annual data collection in determining the pattern and rate of such changes.
The sharp contrast between the lush, species-rich
plant communities at the bird-impacted sites and
the nearly barren sites outside that influence (Fig.
1 and 2) has been better documented on Surtsey
than at any other primary succession site in the
world. Insect diversity has also increased due to
the fertilization effect of the birds (Erling Ólafsson, pers. comm). There is an urgent need to understand how fertilization (whether from birds or
anthropogenic sources of pollution) impacts biological communities – particularly in the context
of rehabilitating damaged lands. One suggestion
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Fig. 1 The bird nesting area in Surtsey is clearly seen from a
distance due to the impact of the birds on the vegetation.
(Walker & del Moral 2003) is that fertilization inhibits successional development and rehabilitation
by favoring dense swards of vegetation. Surtsey is
an ideal place to pursue such studies that will have
important practical applications.
Island biogeography
Rarely are the flora and fauna of an entire, intact
and undisturbed island recorded as they accumulate. Surtsey provides an excellent opportunity to
understand colonization, extinction and carrying
capacity of one island ecosystem. Additionally, as
the island erodes in size, species numbers may decline. Such direct tests of the classic island biogeography concept (MacArthur & Wilson 1967) are
invaluable and rare.
Additional opportunities
There are many other, non-destructive measurements that could be made on Surtsey that would
Fig. 2 The vegetation within the nesting area in Surtsey is lush
and species rich compared with the area outside seen in the
background.
Surtsey Research (2009) 12: 149–151 www.surtsey.is
further our understanding of primary succession.
These include studying nutrient dynamics (particularly of nitrogen and phosphorus) and how these
cycle through the increasingly complex yet still relatively simple ecosystems; linking nutrient fluxes to
changes in both vascular plant and belowground
invertebrate populations; measurements of carbon
accumulation by species and location (above and
below ground); the roles of herbivory and mycorrhizae in succession and consequences of escape
from mainland herbivores; closer examination of
microhabitats where plants colonize and how these
are partitioned among functional groups; and the
role of spatial aggregation of plants in succession.
Finally, we want to emphasize that understanding scientific principles about primary succession
has direct value to society, particularly in terms of
improving our ability to restore severely damaged
ecosystems.
VULNERABILITY AND HUMAN VISITATION
The new biota on Surtsey is vulnerable and at
risk to disturbances, both natural and anthropogenic. The main natural disturbance on the island
is the erosion of its coast that has occurred since
it was created (Jakobsson et al. 2000, Jakobsson &
Gudmundsson 2003). Any visit to Surtsey causes
some disturbances to the island, including trampling and possible introduction of species. However, with the current strict control of access to the
island that risk should be kept minimal.
There has been some debate, mainly amongst
the local people from the Westman Islands, about
releasing the strict closure of Surtsey and allowing
some controlled tourism on the island. This has
been seen as a possible way to promote the tourist
industry in the area and counteract some of the
decrease in employment and economic deprivation on the islands. In spring 2005, a local representative to Parliament formally asked the Minister
of Environment whether there were any plans to
allow tourists to enter Surtsey. On that occasion
and again at a workshop held in Heimaey, Westman Islands in September 2005 on Surtsey and its
management, the Minister said that there were no
plans to change the management and strict control of access to Surtsey. We welcome this statement
and emphasize the importance of it for future
studies on primary succession on the island. Apart
from the risk of increased anthropogenic disturbance with tourism on Surtsey, more frequent visits
would jeopardize the continuing study of primary
Surtsey Research (2009) 12: 149–151 www.surtsey.is
succession. In harsh climates such as exist on Surtsey, human impacts can have large and long-lasting impacts on the environment (Komárková &
Wiegolaski 1999).
CONCLUSION
Ecological research on Surtsey is unusual and
valuable to science for many reasons enumerated
above but it is unique in its restricted access. We
strongly urge the Environment Agency of Iceland
to continue its current policy of limited access.
Such a policy best advances our understanding of
the development of biotic communities and leads
to better land management and restoration practices.
ACKNOWLEDGEMENTS
We thank Borgthór Magnusson for inviting these
comments and the biological research group for
sharing their knowledge and enthusiasm with us
during our visit to Surtsey. We also thank the Surts­
ey Research Society for ensuring the long-term value of Surtsey as a research laboratory for primary
succession and Dr. Sturla Fridriksson, who initiated
the successional studies, for his invaluable foresight
at the time.
References
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